Magazanik L G, Fedorova I M, Kovalevskaya G I, Pashkov V N, Bulgakov O V, Grishin E V
Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the U.S.S.R., Leningrad.
Neuroscience. 1992;46(1):181-8. doi: 10.1016/0306-4522(92)90017-v.
A homogenous protein of 120,000 mol. wt isolated from black widow spider (Lactrodectus mactans tredecimguttatus) venom and referred to as alpha-latroinsectotoxin was highly potent (4 nM) in the induction of an increase of the frequency of miniature excitatory postsynaptic potentials in blowfly (Calliphora vicina) larvae neuromuscular preparations. In the frog nerve ending, however, even 50 nM alpha-latroinsectotoxin failed to affect transmitter release. Pretreatment of insect preparations with alpha-latrotoxin or frog preparations with alpha-latroinsectotoxin did not prevent the specific effect of consequent applications of alpha-latroinsectotoxin (insect) and alpha-latrotoxin (frog), respectively. The binding of labelled [125I]alpha-latroinsectotoxin to insect and [125I]alpha-latrotoxin to bovine membrane preparations was saturable and highly specific. The presynaptic effect, but not the binding of alpha-latroinsectotoxin, was dependent on the presence of divalent cations in the external medium. Mg2+ could readily substitute for Ca2+ and increase of transmitter release induced by alpha-latroinsectotoxin also occurred in Ca(2+)-free solutions. Pretreatment of preparations with 300 micrograms/ml concanavalin A completely abolished both the presynaptic effect of alpha-latroinsectotoxin and its binding to insect membrane preparations. Thus, the phenomenology of alpha-latroinsectotoxin action on insects resembles in general that described for the action of alpha-latrotoxin on vertebrates. The selectivity of alpha-latrotoxin and alpha-latroinsectotoxin seems to be due to differences in the structure of neurotoxin receptors in nerve endings of vertebrates and insects, although the mode of presynaptic action has a great deal in common.
从黑寡妇蜘蛛（间斑寇蛛）毒液中分离出的一种分子量为120,000道尔顿的同质蛋白质，被称为α-拉曲昆虫毒素，它在诱导家蝇（红头丽蝇）幼虫神经肌肉标本中微小兴奋性突触后电位频率增加方面具有高效能（4 nM）。然而，在青蛙神经末梢中，即使50 nM的α-拉曲昆虫毒素也未能影响递质释放。用α-拉毒素预处理昆虫标本或用α-拉曲昆虫毒素预处理青蛙标本，分别不会阻止随后应用α-拉曲昆虫毒素（对昆虫）和α-拉毒素（对青蛙）的特异性作用。标记的[125I]α-拉曲昆虫毒素与昆虫标本以及[125I]α-拉毒素与牛膜标本的结合是可饱和的且高度特异性的。突触前效应而非α-拉曲昆虫毒素的结合，取决于外部介质中是否存在二价阳离子。Mg2+可以很容易地替代Ca2+，并且在无Ca2+溶液中也会出现由α-拉曲昆虫毒素诱导的递质释放增加。用300微克/毫升伴刀豆球蛋白A预处理标本，会完全消除α-拉曲昆虫毒素的突触前效应及其与昆虫膜标本的结合。因此，α-拉曲昆虫毒素对昆虫的作用现象学总体上类似于α-拉毒素对脊椎动物的作用。α-拉毒素和α-拉曲昆虫毒素的选择性似乎是由于脊椎动物和昆虫神经末梢中神经毒素受体结构的差异，尽管突触前作用方式有很多共同之处。
